IPSAG

Technology Development Needs for the Inflation Probe

•  What are the key immediate areas for development?

•  Where is the technology heading in the near term (<2015) and mid-term (>2015)?

Detector arrays & focal-plane coupling –

Harvey Moseley

Multiplexing -

Kent Irwin

IPSAG

The Inflation Probe Technology Roadmap

Technology Priority Timescale Candidates TRL Detector Arrays

High Sub-orbital experiments TES+SQUID+Antenna HEMT / MMIC

4-5

Optics Medium Sub-orbital experiments Polarization modulators AR coatings

2-5

Coolers Low Develop for space Passive+mechanical+sub-K 3-9

Advanced Arrays

Develop for simplified space implementation. Connects to X-ray, far-IR and optical astronomy

MKID+RF resonator TES+RF resonator

3

Detector arrays & focal-plane coupling Harvey Moseley

Multiplexing

Kent Irwin

IPSAG

CMB Polarization Satellite Mission Concepts

1.4 m Crossed Dragone Telescope - Resolution to measure lensing signal cosmic limits Large Focal Plane - equates to 1000 Planck missions! - Wide band coverage for foregrounds Cooling system - 100 mK - Improved Planck system

L2 Halo Orbit - Scan strategy for large-scale polarization - Simple operations, conventional spacecraft

Experimental Probe of Inflationary Cosmology CMB community mission developed for Decadal

PIXIE SMEX proposal Multi-mode FTS

CORE ESA 2010 proposal 1.2 m aperture

EPIC-Low Cost JPL concept

30 cm apertures

LITEBIRD Japanese concept 30 cm aperture

Alternative Concepts

The EPIC Intermediate Mission Bock et al. arXiv 0906.1188

IPSAG 4

CMB Polarization Science is Deep and Broad

Inflationary Gravitational Waves B-modes

Scalar Perturbations E-modes

Gravitational Lensing B-Modes

Galactic Magnetic Fields E & B-Modes

•  Neutrino mass hierarchy •  Dark energy at z > 2

•  Precision cosmology •  Departure from scale inv. •  Reionization history

•  Star formation •  Large-scale fields

•  GUT energy scale •  Large field inflation •  nt / r consistency test

4 yrs

CMB Polarization Spatial Power Spectra

E-mode patterns B-mode patterns

IPSAG

Detectors for CMB Polarization

•  The detection of B-mode polarization of the CMB requires large numbers of high efficiency polarimetric detectors operating at the background limit aganst the CMB.

•  Detectors with adequate thermal sensitivity are well developed. The primary technical challenges are to provide highly integrated polarimeters with uniform characteristics in large arrays (~104 detectors)

5

IPSAG

Primary Detector Requirements

•  High optical efficiency •  Polarization sensitivity •  Integrated filtering

– Uniform across array, adaptable for all required bands

•  Beam formation – Matching for the two polarization states – Uniform across array

6

IPSAG

Additional Requirements

•  Noise characteristics – Allowable 1/f corner depends on

implementation •  Environmental sensitivity

– Particle events •  SEU – dead time •  Parametric changes

– Sensitivity to experimental parameters •  Should be logged at required rate and sensitivity

7

IPSAG

Additional Requirements

•  Ease of integration –  Independently testable integrated focal plane

•  Choices of scales of modularity depend on experimental details

– Simple electrical interface (microwave multiplexing?)

– Thermal interfaces may be challenging for large focal surfaces

– Filtering to limit radiative loads probably easier if telescope is cold

8

IPSAG

Areas for Immediate Development

•  Arrays for current ground based and balloon borne experiments – ~ 103 element – SQUID MUX readouts

•  Optimization of feed structures and coupling

•  Optimization of Detector Production Process – Uniformity of parameters across wafer and

from run to run

9

IPSAG 10

Current CMB Research: Sub-Orbital and Ground-Based

Experiment Technology Resolution (arcmin)

Frequency (GHz)

Detector Pairs Modulator

US-led Balloon

COFE HEMT/MMIC 83/55/42 10/15/20 3/6/10 wire grid EBEX TES 8 150/250/410 398/199/141 HWP PIPER TES 21/15/12/7 200/270/350/600 2560 VPM SPIDER TES 60/40/30 90/150/280 288/512/512 HWP

US-led Ground

ABS TES 30 150 200 HWP ACTpol TES 2.2/1.4 90/145 1500 - BICEP2 TES 40 150 256 - C-BASS HEMT 44 5 1 φ-switch CLASS TES 80/34/22 40/90/150 36/300/60 VPM Keck TES 60/40/30 96/150/220 288/512/512 HWP POLAR TES 5.2 150 2000 - POLARBeaR TES 7/3.5/2.4 90/150/220 637 HWP QUIET HEMT/MMIC 42/18 44/90 19/100 φ-switch SPTpol TES 1.5/1.2 90/150 768 -

Int’l Ground

AMiBA HEMT 2 94 20 Int. QUBIC TES 60 90/150 256/512 Int. QUIJOTE HEMT 54-24 10-30 38 -

•  Push to higher sensitivity than Planck: new detector array technologies •  Focused on B-mode science: target small, deep fields •  Explore the diversity of technology approaches •  Test new methodologies for systematic error control •  Expect rapid progress in Inflationary B-mode limits in next few years

IPSAG

Elements of Detector Design

•  Optical Coupling – Horns, lenslet + antenna, phased array

•  Polarization sensitivity •  Microwave circuitry

– Transmission lines – Filters – Components – Hybrids, etc. – Detector coupling

•  Distributed vs lumped

11

IPSAG 12

Sensor Arrays

Lens-Coupled Antennas

Feed Coupled

Planar Antennas

Optical Coupling To reach the sensitivity required for the Inflation Probe, we need

•  Polarized detectors with noise below the CMB photon noise (much lower NEP).

•  Large frequency coverage with many bands over 30 GHz-1 THz

•  Large numbers of detectors (1->10 kpixel)

•  Exquisite control of systematics

•  The most mature large polarimeter array sensor, the superconducting transition-edge sensor, is now being fielded in ground-based and suborbital experiments.

•  Three optical coupling options are being developed and deployed. New work will be required to project the performance of these options in a satellite environment.

•  MMICs are also being developed at a lower level

SPTpol 150 GHz

BICEP-2 150 GHz

POLARbear

IPSAG 13

Optical coupling / beam forming ACTpol feeds

Feedhorn arrays •  Long heritage in flight missions •  Excellent beam symmetry & crosspol •  ACTpol, SPTpol, ABS, CLASS Phased antenna arrays •  Compact; very low mass, simple •  BICEP-2, Keck, SPIDER, POLAR Lenselet arrays •  Large bandwidth •  POLARbear

BICEP-2 phased arrays

POLARbear lenselets

Three options are being pursued to meet Inflation Probe requirements

IPSAG

Feedhorn-coupled Polarized Detectors

Probe Antennas

TES (H)

TES (V)

Filter Magic Tee

X-over

Wollack, Moseley, Denis, Stevenson, Chuss, Rostem, U-Yen (GSFC)

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IPSAG

Variable-delay Polarization Modulators (VPMs)

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Vary the phase delay Between orthogonal Linear polarizations- Leads to a modulation Of a single linear Stokes parameters with Residuals & systematics Confined to the circular Polarization channel

Concept

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CLASS Prototype grid

IPSAG

Multi-Moded Polarization-Sensitive Detector

30x  collec)ng  area  as  Planck  bolometers  

Photon  noise  ~  (AΩ)1/2  Big  detector:  Negligible  phonon  noise  

Signal  ~  (AΩ)  Big  detector:  S/N  improves  as  (AΩ)1/2    

PIXIE  detector:  AΩ  =  4  cm2  sr  Fill  factor  =  11%  NEP  =  0.7  x  10-­‐16  W  Hz-­‐1/2  

IPSAG

Detector Element Challenges

•  TES – Conductance – Saturation Power

•  Process control on large spatial scales •  A priori prediction of conductance to minimize

iteration – Sensor Noise

•  Develop designs with predictable and understandable noise to facilitate optimization.

–  Should reduce time required to optimize a system

17

IPSAG

Near Term Progress

•  Many fielded polarimeters, some with second and third iteration focal planes – Significant design, production, test, and

operation experience •  Improving understanding TES thermometers,

allowing improved designs •  Improved RF circuit designs and production

•  Better test capabilities for focal planes •  Better understanding of best ways to organize

focal planes

18

IPSAG

Bolometers at Low Frequencies

•  TES bolometers operating at low temperatures can reach the sensitivity required for background limited operation for low frequency bolometers (40 GHz, e.g.)

•  Given demonstrated high efficiency coupling, there is no reason to doubt they will function at fundamental limits at these low frequencies – CLASS has robust demonstrations of efficiency

19

IPSAG

Beyond 2015

•  Existence of quantum limited amplifiers allows vastly simplified detector arrays of many kinds – TES, MKIDs, and semiconducting bolometers

•  Production on larger wafers may change approaches for focal planes

•  Spectropolarimeters made possible by improved microstrip circuits and greater ease of multiplexing

20

IPSAG

Beyond 2015

•  The role of MKIDs in this high power, long wavelength application is not yet clear, but should be within the next 5-10 years.

•  Potential benefits are: – Possibly simpler production process

•  Complexity may be dominated by other circuit elements

– High speed of response •  Less dead time from particle events •  Operation in ionizing radiation field must be

demonstrated 21

IPSAG

Conclusions

•  An active ground and balloon program is driving the development of the first generation of CMB polarization focal planes

•  This work, combined with a robust detector development program can produce vastly simplified high performance arrays with can be flown in a CMB space mission at low risk.

22